Projectile testing machine



Aug. 9, 1949. A. v. MAsKET ET AL 2,478,663

PROJECTILE TESTING MACHINE Filed March 29, 1946 2 Sheets-Sheet l'lllllll AlfEERT-/:MAE KET,l .LELAN D EL 5 N EDDY, JE55-EWEEAM5,

Aug 9, 1949- A. v. MAsKET ET Al. 2,478,663

PROJECTILE TESTING MACHINE Filed March 29, 1946 2 Sheets-Sheet- 2 lu/umm.ALBERT VMAEKET, l LELANDELEI NDDDY, J5EE' EWEEAME.,

Patented Aug. 9, 1949 PRGJECTILE TESTING MACHINE Albert V. Masket,Leland B. Snoddy, and Jesse W. Beams, Charlottesville, Va.

Application March 29, 1946, Serial No. 658,304

(Cl. 7S-66) 4 Claims.

This invention yrelates to a pneumatic device for spinning at highvelocities objects such as bullets and artillery shells in order to testtheir stability. The objects are rotated on an axis of symmetry, free ofany direct mechanical connection or thrust, by the action of an air jet.

An object of this invention is to provide means for spinning at highspeed on its geometric axis, a bullet or an artillery shell, in order totest its degree of dynamic unbalance.

A Afurther object is to provide means for automatically indicating anunsatisfactory degree of unbalance of the spun object, so as to providemeans enabling routine inspection of same. Another object is to spin athigh speed on their geometric axis, ballistic objects such as artilleryshell fuzes so as to permit study or routine inspection of the action ofthe arming pin at high speed. Further purposes will become evident fromthe following descriptions and claims.

The present best use of our invention appears to be in the selection ofhigh grade bullets for small arms ammunition, the selection being madeon the basis of dynamical asymmetry about the geometric axis. A bulletwhich is dynamically asymmetrical about its geometric axis is unbalancedso that its axis of spin in flight is not coincident with its geometricaxis. There is ample evidence that the spread of a pattern of bulletsred at a target can be correlated with the amount of dynamic unbalanceof the individual bullets.

It is therefore important when special accuracy of nre is required thatthe bullets used be in substantial dynamic balance.

In the drawings:

Figure 1 is a Lfront elevation in partial section on line I-I of Figure2 of a preferred embodiment of our invention,

Figure 2 is a sectional view on line 2-2 of the device shown in Figure1,

Figure 3 is a plan view of the stator and associated contact makingmeans of Figure 1,

Figure 4 is a sectional view taken on line A--d of Figure 3,

Figure 5 is a sectional view taken on line 5-5 of Figure 3,

Figure 6 is a sectional view taken on line 6--6 of Figure 3,

Figure 7 is a disassembled perspective view of the stator showing thestator retainer and contact strips.

Essentially our invention consists of a hor-izontal stator or troughdimensioned to receive the bullet or other object to be tested, andperforated in a plane normal to its axis to provide an eccentricallydisposed jet through which a stream of air or other gas under pressurestrikes eccentrically against :a bullet placed in the trough. The rapidstreaming ofair around the bullet provides torque to spin the bullet,and also generates suiiicient Bernoulli force to keep the bullet inplace due to the stabilizing effect of zones of diminished pressureresulting from the high velocity of the contracted stream of escapinggas, both in the circumferential and in the axial directions. The statoris flexibly mounted to permit vibration thereof, which will be impartedto it by either staticV or dynamic unbalance of the bullet. If vibrationof the stator exceeds a predetermined amount, the bullet is rejected asunsatisfactory. In the embodiment shown, for routine inspection purposesa contact between a member fixed to the stator and an adjustablestationary member is used to close a signal'circuit to indicate that thebullet being tested is unsatisfactory.

Referring to the iigures, the stator I, preferably of light plastic orsimilar material, is drilled at 2 to provide an eccentrically disposedjet, and is exibly mounted on an air hose 3 which furnishes air underpressure to jet 2 through air hose extension 4, which is firmly fastenedto the air house by clamp 5. Air hose 3 is made of rubber or anysuitable material of similar characteristics and is firmly held by arigid tube 6 which passes through a hole in metal support plate 1 toposition the stator. A certain amount of stator vibration is thuspermitted due to flexibility of air hose 3.

Stator retainer 8, best seen in Figure 7 is fastened to the stator I byany suitable means such as screws. This retainer serves to reinforce thestator I. Contact connecting strip 9 and -contact strip I0 are .fastenedto stator I by screw II. Contact connecting strip 9 is provided with abinding post I2 for connection of lead I3 from the signalling circuit.This circuit leads from plug I4', which may -be connected to anysuitable source of electricity, through lead I3, connecting st'rip 9 andcontact I0, which upon suicient vibration of stator I will make at leastintermittent' contact with contact point I4.

An inexpensive micrometer I5 maybe cut down to provide an adjustablecontact point I4, thereby permitting ne gradation in adjustment to bemade, or a ne contact point adjustment may be provided by any otherknown means. In the embodiment shown we use a micrometer suit- 3 a-blycut down and screwed to a mount I6 which is in turn fastened to support'plate I (Figure 6).

The signal circuit continues from contact point I4, through themicrometer and mount IS and plate 1 to binding post l1, through lead IBto switch I9 thence through lead 20 to signal lamp 2| and through lead22 back to plug lll.

The entire assembly is mounted in a housing 23 provided vttht adjustinglegs.2'4toppermit leveling of stator I. "Two lead platesare "shown oneon either side of the bottom o1 box 23, to add stability and to aid inabsorbing vibrations.

The side 24 containing the signalflampl. and the side 25 containing thestator and contacts are hinged at 26 and 21 respectivelytofa'c`ilit'ateac-Y cessibility. Hooks 28 and 29 cooperatingfyvith brads28a and 29a respectively arefshownnfor keeping the respective hingedsides closed, a1- though it is obvious that any other-suitable fasteningmeans may be used.

.':Itwill heapparentmhat itheicontact means are prmridedz for;fconveniencezgin lroutine .finspection .-ftandthat:Nisualiobsenvationr'off,the vibration of i the .'statorz'will`provdeuusefultinfnrmation regardiing theA stability of thefbullet.Also,fstroboscopic -L-inspdction of lthe: builetrflby; known means, Vcanbe nntilized tot provide: detailed :information regard- 2 ing'nstheeangular cfpnsition Kofi' unbalanced of i :the rfbullet.

.We: claim:

f 1,iA spinning device frfor @testing *dynamic noalance:comprising; aA'stator' having a curved i innerrsurface:` comprising; etihorizontallydisposed tttrough ziiimensioned.dao:` receive *an-fy object :to betestedntherezbeing acjetonrice inv thestator; r eccentricallyuiiisposdrelative .ato `fthe 'axis 1' of :icurvature `of;saidistattorssurfaceand'jcommunicat- .'ingrwith. 'ther curvedr inner -surface,imeans forntsupplyingfgas underapressure. zto-said jet rorifice f andi-flexible:supportzmeans for Isaid stator.

-;.2..A @spinning cdevice for :Jtesting .idynamic balance comprising; astator havingfaL curved ffinnensurface dimensioned :to receive anfobject to becftested f andA Aformingfia l1orizontal1y disposedfftronghtlof.-vvhichr one; horizontale-edge ishigher than theotherzhorizontal edge; there -heing a:jet oriiice in the fstator-eccentricallyi disposeditoward the isaid".highery edgefin a lplanenormal tothe .zA-supporting meanszfonsaid staton-tandzmeans forsupplying gas `,under pressure to. said .jet orce to said stator, asecond contact normally spaced from said first contact but arranged tofbe contacted by said first conta-ct upon a predetermined degree ofvibration of said stator, an electric cir- 'cnitrinclu'dingaasignalalamp and said contacts,

l0J *saidfcircuitvbeing so arranged as to be closed upon the touching ofsaid contacts, whereby a predetermined degree of vibration of saidstator may ,berfindicatedby the closing of the signal lamp circuit.

: 24.l-"fAsg-'spinning`1device for testing dynamic f-fbalancecomprising; a horizontal stator having a .curvednnensurface dimensionedto receive an object to be tested, there being a jet orifice in thelistator eccentrically disposed relative to the axis of curvature ofsaidi stator surface in a plane inormalrtdaidi axistand'. communicatingwith the c clawed-inner surf-acemn'eans for-asupplying:A gas.undenrpressureato :saldi-jet orifice; sexihlefsupport meansizfor: said;istatcr, 4anx.electrical circuit? inc .cludingr azisignallingdevice,.`normally fixed contactsmeansi andimovahle' 4contacto means rigidly :iattached-.to said'statorafor cooperating Awith said.axedsconta'ctimeansiwhereby, uponvibration' o1 :f'saidf statorrbeyondra; predetermined` point said 30 circuit will loeclosed.toxsaidielectrcal signalling cdevice, aihousingvior saidspinning: device, ad- .;'justable supporting rmeans `for ffsaid f,housing w wherebyssad stator, maybeadjusted to a horiffzontahpositions.adjustingLmeans -or Narying 'the'.;distance'rhetweenwsaifrlnormallyxeda and said wibrating contactsgzandahinged coverifonfsaid frhousing; sainty signallingedevicelbeingrsupncrted 1:; upon saidzhinged cover.

L im :.ALBERT V5 MASKET.

.LELAND {B #SNODDY L JESSE NVMBEAMSl REFERENCES- CITED 5I'The.following` references are of @record in the il file offthis-:patent:

l UNITED l' STATES PATENTS wNmhber 'Name Date i 1,'293;984 "iThompson'Feb. 11; 1919 ;.2,012;780 Taylor ;Aug. 27, 1'935 2,353,150 Dietz July'11, 1944

